JPH079536A - Extrusion head for extruding multi-layer tubular item - Google Patents

Abstract

PURPOSE: To provide a polymer resin extrusion head for stably performing the extrusion molding of a tubular article having a multilayered structure by using a plurality of resins different in viscosity. CONSTITUTION: In order to extrude a plurality of resins different in viscosity to stably mold a tubular article having a multilayered structure and to minimize an unstable flow, those resins are prevented from being combined into a multilayered structure before they reach a place 36 near to the outlet 39 of an extrusion head. In order to help to minimize the unstable flowing distance of the resins extruded from annular outlets 47, 48, 49, the inside layer of the multilayered structure is finally added from the annular outlet 49. In this case, if all of the constitutional portions of the multilayered structure are combined at a place within 4" between the outlets of the extrusion head, the unstable resin blow is minimized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to resin extrusion equipment, and more particularly to an extrusion head for producing tubular articles such as parisons.

[0002]

BACKGROUND OF THE INVENTION A parison, a resin / plastic tubular extrudate that is subsequently blow molded into a bottle, is formed in the prior art by a variety of devices, some of which are It includes an extrusion head that extrudes successive layers of plastic resin onto a mandrel. Such a device must be sized so that it can be inserted into a blow molding device for bottles. A typical multi-layer parison extrusion head has a separate inlet for receiving the heated / plasticized resin coming from the individual screw type heating / extruder,
It has individual channels for dispensing / squeezing each plastic resin onto the mandrel as successive layers. Each channel includes an annular balancing / distributing chamber surrounding and surrounding the mandrel for receiving the plastic resin coming from the corresponding inlet. Equilibration chamber
ber), the plastic is fed downwardly and inwardly through a frustoconical transfer passage into tubular extrusion channels formed around the mandrel. The annular extrusion channel communicates outwardly through an inwardly or outwardly flared annular die that includes a conical core member, so that the conical core member is the outer member of the die. The relative axial movement can change the wall thickness of the extruded tubular article.

One particularly useful and successful extrusion head for forming tubular articles such as parisons is disclosed in US Pat. No. 4,798,526. This head is
An annular extrusion channel that includes one or more individual annular extrusion modules that surround each successive portion of a stepped or tapered mandrel to form an annular extrusion channel. But,
It accepts one or more sequentially extruded plastics coming from the module. Each module has a pair of members with mating surfaces in which a balancing / dispensing chamber and a frustoconical transition passage are formed. . The modules of the dies are separated from each other by an annular air space, which prevents heat transfer that would result in a degradation of the low temperature resin.

While prior art devices are generally efficient / effective in extrusion of multi-layer parisons, improvements are desired.

Due to the multi-layer structure, the conventional extrusion head has an annular flow (distance) of a considerable length.
Annular flow (distance) while each successive layer merges
Has a length of 3 to 5 ". This imposes a serious constraint when materials with different viscosities are used. It depends on the relative viscosities and flow velocities of the materials. And can cause instability in the flow due to the generation of boundary waves at one or more of the interlayer interfaces, such waves being absolutely unacceptable in the product. The two-layer flow, where the material flow rate is slow, is unstable.Three-layer flow where the viscosity of the middle layer is lower than in the outer two layers, especially one or both of the outer two layers is relatively Instability when thin: this is a serious constraint, because the choice of material and thickness is usually governed by the desired properties of the blow molded article as a product. Because.

Conventional extrusion heads also form a multi-layer structure from the inner layers first by feeding a layer of resin along the mandrel. This can cause a problem if the inner layer is made of a highly viscous material that distinguishes it from each subsequent layer. This problem limits the shape, layer thickness, and / or composition of the multi-layered parison.

[0007]

SUMMARY OF THE INVENTION Accordingly, one object of the present invention is to provide a tubular extrusion for producing a high quality parison even when the layer structure is unstable.
It is to provide a new and improved polymer extrusion head.

Another object of the present invention is a new and improved tubular extrusion, which allows a wider selection of materials, layer thicknesses and layer shapes for the extrusion parison. To provide a polymer extrusion head.

An additional object of the invention is to improve the circumferential uniformity of the wall thickness of the article being extruded.

A further object of the present invention is to provide improved temperature separation between extrusion modules in a multi-module extrusion head.

A further object of the invention is to provide such a device which allows the inner layers of a multi-layer structure to be added last in succession, whereby the shape of the multi-layer parison, It is to provide additional versatility in layer thickness and composition.

Upon further consideration of this specification and the appended claims, further objects and advantages of the invention will be apparent to those skilled in the art.

[0013]

The above and other objects are achieved with a polymer extrusion head according to the present invention, the polymer extrusion head comprising a mandrel and a plurality of mandrels surrounding the mandrel. An annular extrusion module, each with a resin inlet,
It includes an annular extrusion module having an annular outlet for extrusion of the resin layer and a passageway therebetween. The shape of the annular outlets is such that the resin layers extruded from them combine to form a multi-layer structure, with the last resin layer being added within 4 inches (4 ″) from the outlet of the extrusion head. Is decided.

In another aspect, the present invention provides an extrusion head in which the inner layer is the last layer added to the multilayer structure.

In another aspect, the invention combines the feature of short multi-layer flow in a polymer extrusion head with the use of a helical passage extending from the resin inlet to the annular outlet in the extrusion module. .
The passages form multiple convolutions,
It is desirable to open to one frustoconical channel.

In yet another aspect, the present invention uses extruded modules that are spaced apart from each other by the feature of short multi-layer flow (distance) in a polymer extrusion head, the components being independent of other modules. Combined with. This allows the spacing between the modules to increase the temperature spacing.

[0017]

The various other objects, features, and attendant advantages of the present invention will be more fully appreciated when the invention is better understood by consideration in connection with the accompanying drawings. Let's do it. In the drawings, like reference numerals are used to refer to the same or like parts throughout the several views.

As shown in FIG. 1, one embodiment of an extrusion head according to the present invention is generally axially located along mandrel 34, one behind the other, generally 1, 2, and 3, respectively. A plurality of coaxial extrusion modules, indicated by reference numbers, are included, and an annular channel 36 is defined between the inner surface of the extrusion modules and the mandrel. The channel 36 terminates at the exit 39 of the extrusion head where the tubular article, such as a parison, is extruded.

The modules 1, 2, and 3 of FIG. 1 are integrated frustoconical sections 5, 10, 15, which form part of the modules.
And 20 are provided. It is not necessary to use integrated components to form a module. For example, FIG. 3 shows the individual modules 6, 11, and 16
1 shows an example of an extrusion head using Modules 6, 11, and 16 include upper sections, 40, 50, and 60, respectively, and lower sections, 41, 51, and 61, respectively, to form the module. The upper and lower sections interlaced with each other define only one module each.

Referring again to FIG. 1, the resin inlet 46 for the module 2 is shown on the perimeter of the sections 10 and 15 of the combination. Each module contains one resin inlet. The resin inlets for modules 1 and 3 are
Not shown as it is located elsewhere on the extrusion head. Resin inlet 46 is a combination of sections 10 and 1
5 are formed by machining both surfaces.

Modules 1, 2, and 3 each have one annular outlet, 47, 48, and 49, respectively.
It has one passage from the resin inlet to the annular outlet for each module, 100, 101 and 102, respectively. The passages 100, 101, and 102 are helical in shape near the resin inlet 46 and progressively open into a frusto-conical shape. The passages 100 and 101 subsequently open into an annular shape closer to the annular outlet.

Sections 5, 10, 15, and 20
Surface 80, 81, 82, 83, 84 of each combination of
And 85 have frusto-conical sections with the apexes downstream. Face 80 of paired combinations
The upper frusto-conical portions at 81, 82, 83, 84 and 85 have the same taper so that they fit together as a sealing engagement. This results in about a quarter of the first turn of passageways 100, 101, and 102.
So 90 ° is closed. Combination faces 80 and 81,
The portions of the frusto-cone below 82 and 83, 84 and 85 are 90, respectively at points on faces 80, 82 and 84
The taper ahead of 91 and 92 is different. This allows each passage, preferably progressively thicker, to open progressively into one annular shape, so that the passages 100, 10
1 and 102 are annular outlets, 47 and 4 respectively
8 and 49 are defined.

The spiral portion of passages 100, 101, and 102 is formed by the outer surface 8 of sections 5, 10, and 15.
It is formed by machining 0, 81, and 82. Desirably, at least two complete turns of passageways 100, 101, and 102 extend beyond points 90, 91, and 92.

The annular outlets 47, 48, and 49 push the tubular resin layer into the annular channel 36 at different downstream points so that the resin layers move one after the other into the annular channel 36. And the extruded tubular layers are allowed to assemble one after the other into a tubular multi-layer structure. Circular exit 49
Is the last annular outlet in the series and is located very close to the outlet 39 of the extrusion head. This position is preferably within 4 inches (4 ") of the extrusion head outlet 39, and most preferably within 1". This allows the module 1 to add a foreign resin to the multilayer structure. This is because the flow of the unstable combination formed in the extrusion head after the foreign resin has been added is minimized. The apparatus of FIG. 1 has annular outlets 47, 48, and 49 in that all tubular resin layers combine within a short distance from the outlet 39 of the extrusion head to form a tubular multilayer structure. It has the desired shape. The multilayer flow begins at the outlet 48 and exits the extrusion head 39.
Is over. All tubular multi-layer structures
It is desirable to combine within 4 "with the outlet of the extrusion head, and most preferably within 1". The annular outlet geometry shown in FIG. 1 is unusual in that the inner layer is the last layer to be combined into a multilayer structure. The multilayer structure begins to be made away from the mandrel and the resin layer flowing along the mandrel is added as the last layer. This occurs because the annular ring 4 above the section 10 separates the resin supplied along the mandrel 34 from the resin in the passages 101 and 102, the latter resin forming a multilayer structure. Because it makes it possible to start being made.

Sections 5, 10, 15, and 20
Are coupled together by bolts (not shown) extending through bolt holes 160. Mandrel 34
Are secured to sections 5, 10, 15, and 20 by means not shown in FIG. In FIG. 4, the mandrel is secured by a nut 114 at the top of the extrusion head. It should be understood that the means for securing the module or mandrel may vary considerably.

Referring to FIG. 1, the mandrel 34 is tapered, but this is not required. This is because the tapered portion does not limit the annular channel where multiple layers are combined to form a multi-layer structure. The diameter of the mandrel 34 is chosen according to the desired thickness of the layer being extruded along its length.

The die 25 is mounted by a die clamp 163 and bolts (not shown) in the bolt holes 162. Die core 128 is threaded onto shaft 142, which extends slidably through the lumen of mandrel 34. The die 25 has its opening tapered or reduced in diameter to accommodate the taper of the die core 128 so that the proper wall thickness of the tubular article being extruded is maintained. The die, its openings, and the means for securing the die are sometimes quite different.

The wall thickness in the lower portion of the annular channel is preferably smaller than in the upper portion of the annular channel to ensure that the layers of the multilayer structure are firmly interconnected. In the preferred embodiment, the die core 12 has a central axial bore 152 for injecting gas into the parison being extruded to prevent it from collapsing.
8 and the shaft 142.

Turning to FIG. 2, there is shown another embodiment of the extrusion head of the present invention in which a plurality of coaxial heads, generally designated 201, 202, and 203, respectively. Extrusion modules are axially positioned one behind the other along a mandrel 234 to define an annular channel 236. Module 20
1, 202 and 203 are provided with integrated annular sections 205, 210, 215 and 220. Resin inlet 246 and annular outlets 247, 24
8 and 249 are similar in shape to the embodiment of FIG.
The passages 200, 201, and 202 have different shapes than those used in the embodiment of FIG.
The passages 200, 201, and 202 have a spiral shape near the resin inlet, and gradually open to one annular shape near the annular outlet. The spiral passage of FIG. 2 is concentric and coplanar, unlike the passage shown in the embodiment of FIG. The passages need not be helical in shape. The passageways may be of conventional heart shape, or "coat hanger" shape.

The mating surfaces 280, 281, 282, 28 of sections 205, 210, 215, and 220.
3, 284, and 285 are annular, and the perimeters of the faces of their combination are sealingly engaged with each other, thereby closing a portion of the turns of passages 200, 201, and 202. Pairs of combined faces 280 and 28
The inner portions of 1, 282 and 283, 284 and 285 have a relatively narrow thickness, thereby allowing passage 20
It is possible for 0, 201, and 202 to progressively open into one annular shape, defining annular outlets, 247, 248, and 249, respectively.

Annular outlets 247, 248, and 249
In a manner similar to that of the extrusion head of FIG. 1, the resin layer is extruded at each downstream point into the annular channel 236, whereby the extruded tubular resin layers are combined in tandem. It is possible to be a multi-layer structure of. The annular outlet 247 is the last annular outlet in the series and is located very close to the extrusion head outlet 239. This position is preferably within 4 ″ from the exit of the extrusion head, and most preferably within 1 ″.

Annular ring 20 on segment 210
4 separates the resin in the passage 200 along the mandrel 234 from the resin in the passages 201 and 202, thereby shortening the flow path of the multilayer structure that the resin forms in the unit. , The order of combination is controlled so that the inner resin layer is finally combined in the multilayer structure.

The other components of the extrusion head shown in FIG. 2 are similar to those of the embodiment shown in FIG.

FIG. 3 is another embodiment of the extrusion head of the present invention, in which a plurality of mutually independent coaxial extrusion modules 6, 11, and 16 are provided.
Are located axially back and forth along the mandrel 334. As described above, sections 40 and 41 form module 6, sections 50 and 51 form module 11, and sections 60 and 61 form module 1.
6 is formed. The resin inlet is similar in shape to that in the embodiment shown in FIG. 2, but the passages 300, 301,
And 302 are differently shaped and the annular outlets 347, 348 and 349 feed (resin) into the annular channel 336 in different spacing relationships. Both variations occur because the modules 6, 11 and 16 are independent of each other with air gaps 300, 301 between them. The air space between the modules creates a temperature differential within the extrusion module and prevents its degradation when a temperature sensitive resin is used.

Segments 41, 50, 51 and 60
Annular rings 310, 320, 330, and 3 on the table
40 separates the resins in passages 300, 301, and 302 from each other until approaching the exit 339 of the extrusion head, preferably within 4 ″ of the exit 339 of the extrusion head. The annular rings also allow the layers to finally join the multi-layer structure, with the other components shown in FIG. 3 being substantially similar to those in FIG. Bolts 380 and 390 are shown securing the segments 40, 41, 50, 51, 60, and 61.

FIG. 4 illustrates one parison extrusion machine having a conventional controller 460 for controlling the vertical position of the shaft 442 in the mandrel 434 of the extrusion head 410. There is. Extruded parisons often have varying thicknesses from bottom to top. That is, the bottom portion of the bottle requires a relatively thick wall to prevent pressure swelling of the contents of the bottle, such as carbonated beverages. Controller 4
60 includes modules 414, 416, 418, and 4
Varying the extrusion pressure of each extruder 424, 426, 428, and 430 feeding the 20, thereby varying the thickness of each layer extruded relative to the other layers in the manner normally done. You can For example, the thickness of the structural layer may be reduced at the top of the bottle while the barrier layer remains uniform across the height of the bottle. The parison 432 emerging from the die 425 is shown.

One example of a parison suitable for being bottled by blow molding is an amorphous polyamide.
The embodiments described above having inner and outer layers of polycarbonate with an intermediate layer of yamide) and regrind have several advantages over prior art extruders. That is, the annular outlets limit the flow distance of the multilayer structure in the extrusion head, thereby allowing the unstable combination to be shaped into a parison for blow molding. For example, a high viscosity polycarbonate resin can be more easily formed into a parison with a low viscosity resin. Minimizing the flow distance of the multilayer structure reduces the chance of boundary waves forming at the boundaries between layers. Still further, an advantage of the preferred embodiment is the use of a spiral passage having multiple turns that progressively open into one annular passage. With this shape, the pressure difference near the resin inlet is canceled by the pressure difference in the upper portion of the annular passage. This obviates the need for an annular pressure balancing / dispensing chamber, which was generally required in prior art tubular article extrusion equipment. When this spiral channel is used, embodiments of the present invention provide excellent circumferential layer thickness uniformity.

Those examples which allow the inner layers of the multilayer structure to be added last are:
Allows for greater variation in layer shape, layer thickness, and layer composition. These examples allow more freedom to utilize low flow / high viscosity resins as the inner layer in multilayer tubular extrusion.

Another preferred embodiment of providing an air space between adjacent mutually independent annular modules provides the advantage of greater (to some extent) temperature separation.

Although the embodiments described above are directed to making parisons for use in blow molding into bottles, the annular extrusion head disclosed herein can be used in many other tubular articles. , For example, blow-molded films formed by longitudinally slitting tubular moldings with or without blowing, pipe extrusions or other cross-sections with long profile extrusions, wire coatings, polymers Manufacture of glass mat reinforced sheets extruded onto glass fiber mats from one or more annular extrusion heads with rectangular central bores, pultrusion sheets, rods or profile products. Suitable to do.

Without further explanation, one of ordinary skill in the art will be able to best utilize the present invention using the above description. Therefore, the specific preferred embodiments described above are to be construed as illustrative only and not limiting in any way not disclosed.

All disclosures (contents) in the applications, patents, and publications mentioned above and below are hereby incorporated by reference.

From the foregoing description, those skilled in the art can easily ascertain the essential characteristics of the present invention and, without departing from the spirit and scope thereof, to adapt the present invention to various applications and conditions, Various modifications / variations of the present invention may be made.

[Brief description of drawings]

1 is a cross-sectional view of one extrusion head half for extruding a multi-layered parison according to the present invention.

FIG. 2 is a cross-sectional view of another extrusion head half for extruding a multi-layered parison according to the present invention.

FIG. 3 is a cross-sectional view of another extrusion head half for extruding a multi-layered parison according to the present invention.

FIG. 4 is a schematic view of a parison extrusion machine including an extrusion head with an air space between modules.

[Explanation of symbols]

1, 2, 3, 6, 11, 16, 201, 202, 20
3, extrusion module 4 annular ring 5, 10, 15, 20 module section 25, 425 dies 40, 50, 60 module upper section 41, 51, 61 module lower section 34, 234, 334, 434 mandrel 36 , 236, 336 Annular channel 39, 239, 339 Extrusion head outlet 46, 246 Resin inlet 47, 48, 49, 247, 248, 249, 347,
348,349 annular exit 80,81,82,83,84,85,280,28
1,82,283,284,285 Combination surface 90,91,92 Position on combination surface 100,101,102,300,301,302
Passage 114 Nut (FIG. 4) 128 Die core 142 Shaft 152 Central axial bore (air flow path) 160 Bolt hole 162 Bolt hole 163 Die clamp 204 Annular ring 205, 210, 215, 220 Annular section 280, 281, 282, 283, 284, 285
Surface of combination 310,320,330,340 Annular ring 380,390 Bolt 410 Extrusion head 442 Shaft 460 Controller 414,416,418,420 Module 424,426,428,430 Extruder 432 Parison

Front Page Continuation (72) Inventor Eric Otto Tosh United States 01254 Richmond Summit Road, Massachusetts 488

Claims (20)

[Claims] 1. A polymer resin extruding head for extruding a tubular article, comprising a mandrel and axially vicinal portions of the mandrel, the annular shape being between the mandrel and the mandrel. A plurality of coaxial, annular extrusion modules defining channels, the annular channels ending at the exit of the extrusion head where the tubular article is extruded, each annular extrusion module comprising: , A resin inlet for receiving and distributing the resin, an annular outlet for pushing the tubular resin layer into the annular channel, and a passage from the resin inlet to the annular outlet. The shape is such that the extruded tubular resin layers assemble one after the other in the annular channel to form one tubular multi-layer structure, and the final extruded tubular Resin layer is determined to join the multilayer tubular structure in the 4 "within at between the outlet of the extrusion head,
Polymer resin extrusion head. 2. The shape of the annular outlets is determined so that all of the tubular resin layers are combined within 4 ″ with the outlet of the extrusion head to form a tubular multilayer structure. The extrusion head according to claim 1. 3. The shape of the annular outlets is determined such that the tubular resin layer which is finally combined with the tubular multilayer structure is an inner layer of the tubular multilayer structure.
The extrusion head according to claim 1. 4. The shape of the annular outlets is determined so that the last extruded tubular resin layer joins the tubular multi-layer structure within 1 ″ from the outlet of the extrusion head. The extrusion head according to claim 1. 5. A passage in the annular extrusion module comprises:
An extrusion head according to claim 1, wherein the extrusion head gradually opens into a ring-shaped space that extends spirally from the resin inlet and continues to the ring-shaped outlet. 6. The extrusion head of claim 5, wherein the passage extending spirally from the resin inlet forms a plurality of spiral turns. 7. A frustoconical space wherein the annular extrusion module is frustoconical in shape, the passages extending helically from the resin inlet to the annular outlet. The extrusion head of claim 1, wherein the extrusion head is progressively open into. 8. Each of the plurality of annular extrusion modules comprises a pair of combined annular segments secured to one another, the combined annular segments comprising:
It is not part of another module, but is axially spaced along the mandrel, thereby avoiding direct heat transfer between adjacent modules there. An extrusion head according to claim 1, wherein there is sufficient air space formed for it. 9. A polymer resin extrusion head for extrusion-molding a tubular article, comprising a mandrel and an axially-adjacent axial position along the mandrel, with an annular shape between the mandrel and the mandrel. A plurality of coaxial, frustoconical annular extrusion modules defining channels, said annular channels leading to the outlet of the extrusion head where the tubular article is extruded, each truncated A conical annular extrusion module includes a resin inlet, an annular outlet for pushing the tubular resin layer into the annular channel, and a passage from the resin inlet, i.e., a spiral extension to the annular outlet, Forming a spiral winding of, and having a passage that opens progressively into a frusto-conical space leading to an annular outlet, the shape of the annular outlet being The extruded tubular resin layers were assembled back and forth in an annular channel within 2 inches from the exit of the extrusion head into a tubular multi-layer structure, the final extruded A polymeric resin extrusion head, wherein the tubular resin layer is adapted to join the tubular multilayer structure within 1 inch from the exit of the extrusion head. 10. The shape of the annular outlets is determined such that the tubular resin layer which is finally combined with the tubular multilayer structure is an inner layer of the tubular multilayer structure. 9. The extrusion head according to item 9. 11. The extrusion head of claim 9, wherein each of the plurality of frustoconical extrusion modules comprises a pair of fixed frustoconical segments fixed to one another. 12. A plurality of coaxial, frustoconical extruding modules are axially spaced along a mandrel such that there is direct space between adjacent modules. 10. The extrusion head of claim 9, wherein sufficient air space is formed to avoid thermal transfer of heat. 13. The extrusion head of claim 9, wherein an annular die is mounted at the end of the mandrel, downstream of the frustoconical extrusion module. 14. The extrusion head of claim 9, wherein the resin inlet of the frustoconical extrusion module is adapted to receive resin directly from the extruder. 15. The resin inlet of the annular extrusion module is adapted to receive resin directly from the extruder,
The extrusion head according to claim 1. 16. A polymer resin extrusion head for extruding a tubular article, comprising a mandrel and axially vicinal portions of the mandrel along the mandrel. A plurality of coaxial, annular extrusion modules defining channels, the annular channels ending at the exit of the extrusion head where the tubular article is extruded, each annular extrusion module comprising a resin Has a resin inlet, an annular outlet for pushing the tubular resin layer into the annular channel, and a passage from the resin inlet to the annular outlet for receiving and distributing The shape of the extruded tubular resin layer is that the extruded tubular resin layers are combined one after the other in the annular channel to form one tubular multi-layer structure, and finally the tubular multi-layer structure. Concrete body combination is extruded tubular resin layer is determined to be a inner layer of the multilayer structure of the tubular polymeric resin extrusion head. 17. The shape of the annular outlets is such that all of the tubular resin layers are 4 ″ between the outlet of the extrusion head and the outlet.
An extrusion head according to claim 16, which is adapted to assemble within to form a tubular multi-layer structure. 18. The shape of the annular outlets is such that the last extruded tubular resin layer joins the tubular multi-layer structure within 1 ″ from the outlet of the extrusion head. The extrusion head according to claim 16. 19. The frustoconical shape of the annular extrusion module is a frustoconical space in which the passages extend spirally from the resin inlet to the annular outlet. 17. A progressive opening into
Extrusion head as described. 20. Each of the plurality of annular extrusion modules comprises a pair of interlocking annular segments secured to one another, the annular portion of the combination forming part of another module. However, they are axially spaced along the mandrel so that there is sufficient air space between adjacent modules to avoid direct heat transfer there. The extrusion head according to claim 16, wherein the extrusion head is formed.